The medical community and society in general have been concerned with reducing the hazardous effects of cigarette smoking for many years. The chemicals contained in cigarette smoke produce unwanted effects, including unpleasant odours and health hazards for smokers and bystanders breathing the smoke.
Of the various chemicals contained in cigarette smoke, nicotine is primarily responsible for the pleasurable effects of smoking. Nicotine replacement devices, such as chewing gums or patches, allow a smoker to obtain doses of nicotine without inhaling the other hazardous chemicals in cigarette smoke and without creating smoke that is hazardous to bystanders. Accordingly, nicotine replacement devices may be useful in programs to reduce or eliminate the smokers' dependency on smoking.
Inhaling nicotine as a powder is an effective way to deliver nicotine to the bloodstream. The inhaled powder is deposited on the inner surfaces of the lungs and absorbed into the bloodstream. However, in addition to their desire for nicotine, smokers are also accustomed to the process of smoking. This process includes one or more of the following: handling the cigarettes, tapping the cigarettes against a hard surface before smoking, tapping the cigarette between inhalations to remove ashes and discarding the cigarette when done. Further, smokers are accustomed to inhaling on the cigarette several times to withdraw the nicotine.
Although hand held inhalers, including hand held powder inhalers, for use by a patient without medical assistance currently exist, they have various undesirable features. For example, many devices are designed for medical conditions where a patient requires immediate delivery of a medicament. These devices deliver the medicament in one or, at most, a small number of inhalations. These devices are not suitable for medicaments that are preferably delivered over several inhalations. Further, these devices rely on air currents that flow directly through or across the medicament which causes some of the medicament to travel at high speed and impact the user's airway rather than enter the user's lungs.
Other existing devices rely on complicated or awkward mechanisms for their use. For example, propellers may be used to rotate a capsule to expel powder by centrifugal force, or various rotating or sliding mechanisms may be used to deposit discrete amounts of powder into the airflow path of an inhaler. These devices are complicated and difficult to use discretely. Similarly, many devices require a person to manually insert a medicament container, such as a capsule of powder, into the device in a manner that breaks the container open, again making it difficult to use the device discretely or conveniently. The expense and size of these devices requires them to be reused whereas it would be more convenient and hygienic to make them disposable.
One inhaler of note is Priestly (U.S. Pat. No. 2,587,215). Priestly discloses a device which uses a sliding mechanism to deliver small portions of powder from a remote reservoir to a chamber. The primary airflow enters this chamber and flows through or across the powder. A downstream air inlet provides a secondary airflow that mixes with the primary airflow coming from the chamber to diffuse the powder mixture. To use the device, a person would need to first insert a capsule into the device, and then manipulate the sliding mechanism to put a portion of powder in the chamber for inhalation.
Another inhaler of note is Cavazza (U.S. Pat. No. 4,338,931). Cavazza discloses a device which has two pre-assembled telescoping components which contain a capsule of powder. Each of the two components has a hollow open ended spike which pierces the capsule when the two components are slid together. Air flows into the first spike, through the capsule and through the second spike to a mouthpiece. The device is compact and easily used, but the direct airflow through the powder would deliver most of the powder at high speed in a single inhalation.
Inhalers which comprise a hollow longitudinally extending member are known. For example, Rose et al (U.S. Pat. No. 5,441,060) discloses a hollow cylindrical member wherein the medicament is stored in a thin annular band or in a porous member. According to this patent, air passing longitudinally through the inhaler entrains the medicament. Slutsky et al. (application No. PCT/CA95/0056) also discloses such an inhaler wherein air passing longitudinally through the inhaler entrains the medicament. In these devices, the air passing through the inhaler contacts the medicament as the air travels directly through the inhaler.